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Post by srbrant on Jun 21, 2017 17:17:52 GMT
Moving back to layouts, I often wondered how a huge (read: more than 500,000 tons) ship would be built. about half as big as this 2552 feet long?! DAMN...
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Post by Enderminion on Jun 21, 2017 17:35:07 GMT
about half as big as this 2552 feet long?! DAMN... 2552 feet and Six inches, but length is one of the least important aspects of ship size, why my Wasp Carrier is 5.8 Megatons in mass
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Post by Dhan on Jun 21, 2017 17:56:53 GMT
It's not the size of the vessel that matters, it's how you use it.
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Post by Enderminion on Jun 21, 2017 18:13:57 GMT
It's not the size of the vessel that matters, it's how you use it. is something people with small ships would say
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Post by srbrant on Jun 22, 2017 5:43:28 GMT
It's not the size of the vessel that matters, it's how you use it. is something people with small ships would say Ohohohoho!
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Post by Hicks on Jun 22, 2017 10:15:29 GMT
What matters most: size, mass, firepower, thrust, dV, or expense?
The answer is victory. All other metrics are irrelevent compared to victory. I would shun the largest, smallest, fastest, slowest, cheapest, most expensive, and everything else in favor of a ship that wins, and so should you.
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Post by The Astronomer on Jun 22, 2017 11:04:23 GMT
What matters most: size, mass, firepower, thrust, dV, or expense? The answer is victory. All other metrics are irrelevent compared to victory. I would shun the largest, smallest, fastest, slowest, cheapest, most expensive, and everything else in favor of a ship that wins, and so should you. The definition of the word 'victory' is pretty vague. A ship that win against every other capship might lose against mini missiles or drones. And yes, 'victory' depends on those factors.
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Post by Easy on Jun 22, 2017 23:18:58 GMT
What matters most: size, mass, firepower, thrust, dV, or expense? The answer is victory. All other metrics are irrelevent compared to victory. I would shun the largest, smallest, fastest, slowest, cheapest, most expensive, and everything else in favor of a ship that wins, and so should you. The definition of the word 'victory' is pretty vague. A ship that win against every other capship might lose against mini missiles or drones. And yes, 'victory' depends on those factors. Lots of research and forethought to make a decision on what will be needed. In practice you're stuck with the equipment that acquisitions and planning decided several years ago. Don't get angry because they're trying to figure out what you'll need 5 years from now or more. Plus with space being big you've got months or years to get the ship to where you might need it, which is another bit of planning. That is unless you're confident enough to have a factory ship with necessary cargo supply to manufacture on demand and retrofit the combat ships you have nearby. Which implies that the manufacturing equipment is portable and effective enough to build the retrofit. I suspect even with advanced 3d printing and computer controlled manufacturing there will be specialty parts that cannot be built outside of a (not portable) specialized factory and logistics chain.
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Post by The Astronomer on Jun 23, 2017 11:30:28 GMT
The definition of the word 'victory' is pretty vague. A ship that win against every other capship might lose against mini missiles or drones. And yes, 'victory' depends on those factors. Lots of research and forethought to make a decision on what will be needed. In practice you're stuck with the equipment that acquisitions and planning decided several years ago. Don't get angry because they're trying to figure out what you'll need 5 years from now or more. Plus with space being big you've got months or years to get the ship to where you might need it, which is another bit of planning. That is unless you're confident enough to have a factory ship with necessary cargo supply to manufacture on demand and retrofit the combat ships you have nearby. Which implies that the manufacturing equipment is portable and effective enough to build the retrofit. I suspect even with advanced 3d printing and computer controlled manufacturing there will be specialty parts that cannot be built outside of a (not portable) specialized factory and logistics chain. That first paragraph took me like five minutes to understand the actual message and not as an 'insult' I initiallly thought it is. I wish I was in one of the literate anglosphere nations ;-; Anyways, with the fusion drives (what you're likely to have in a hundred years' time, unless humanity loses its scientific progress), that might went down to a few months or worst, a few years. That's pretty fast for a space war.
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Post by EshaNas on Jun 24, 2017 7:19:43 GMT
How does one even go 'faster' in space anyway? Burning more D/v? Say I take my 'Fast' Courier with 20 km/s capability (mass ratio nearly 10), for a Mars trip from Earth orbit to Martian Orbit, that's around 12 Km/s needed, if I burn 6 more, would that cut the travel time by a fourth or so...and that's calculated by literally measuring the distance between Earth and Mars and translating the km/s to days/months?
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Post by ross128 on Jun 24, 2017 15:14:35 GMT
Well, due to some practicalities of space "fast" has different metrics for travel and combat.
In travel, you want to get from A to B in the shortest time possible. This means taking the shortest route possible, with the highest average velocity possible. So, the fastest thing would be something with very high dV so it can take a straight shot torch-ship style, burning half its dV accelerating and the other half decelerating so they don't overshoot the target. For acceleration, they just need enough acceleration to burn half their dV before they reach the half-way point of their trip (so they have time to turn around and burn the other half). So in this situation, the higher your dV, the faster you get from A to B so long as you have enough acceleration to make use of it.
If you don't have enough dV for a torch-ship trajectory, things get much more complicated and it becomes a matter of orbital mechanics. For example, if the timing is right that extra 6km/s of dV could maybe allow you to take a shorter trajectory by cutting inside with an elliptical orbit, then circularizing and braking for a capture when you arrive. Burning it at the wrong time on the other hand, could cause you to miss your target entirely. The straight-line distance won't matter here, because you're not taking the straight-line route. The majority of time savings will come from reducing the distance you have to travel, rather than traveling that distance at a higher velocity.
In combat, you're trying to overtake another ship and you'd probably prefer to do so before either of you runs out of fuel. So dV is a bit less important, though you'll at least want to have a bit more than your target so you don't have to worry about running out of fuel before they do. But acceleration will be much more important, because if you have much higher acceleration than your target you can quickly overtake them without having to run them out of fuel first. In this scenario, acceleration is basically your "speed", your ability to perform maneuvers more quickly, and dV is your endurance. You can catch someone by beating them on endurance of course, but you'd probably prefer not to.
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Post by EshaNas on Jun 25, 2017 3:13:15 GMT
Well, due to some practicalities of space "fast" has different metrics for travel and combat. In travel, you want to get from A to B in the shortest time possible. This means taking the shortest route possible, with the highest average velocity possible. So, the fastest thing would be something with very high dV so it can take a straight shot torch-ship style, burning half its dV accelerating and the other half decelerating so they don't overshoot the target. For acceleration, they just need enough acceleration to burn half their dV before they reach the half-way point of their trip (so they have time to turn around and burn the other half). So in this situation, the higher your dV, the faster you get from A to B so long as you have enough acceleration to make use of it. If you don't have enough dV for a torch-ship trajectory, things get much more complicated and it becomes a matter of orbital mechanics. For example, if the timing is right that extra 6km/s of dV could maybe allow you to take a shorter trajectory by cutting inside with an elliptical orbit, then circularizing and braking for a capture when you arrive. Burning it at the wrong time on the other hand, could cause you to miss your target entirely. The straight-line distance won't matter here, because you're not taking the straight-line route. The majority of time savings will come from reducing the distance you have to travel, rather than traveling that distance at a higher velocity. In combat, you're trying to overtake another ship and you'd probably prefer to do so before either of you runs out of fuel. So dV is a bit less important, though you'll at least want to have a bit more than your target so you don't have to worry about running out of fuel before they do. But acceleration will be much more important, because if you have much higher acceleration than your target you can quickly overtake them without having to run them out of fuel first. In this scenario, acceleration is basically your "speed", your ability to perform maneuvers more quickly, and dV is your endurance. You can catch someone by beating them on endurance of course, but you'd probably prefer not to. Thanks. The part I bolded is especially interesting. Though I guess something like the Antimatter-beam core designs do fall to Torch-Ship levels....
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Post by halnordmann on Nov 30, 2019 9:31:59 GMT
srbrant: I am also working on a sci-fi story (main caracter's name is my username), and it has many elements similar to yours (although it is set in cca. 22nd century, and arfical gravity is much more expensive). The horizontal layout is surely useful for cargo transport (try stacking containers to a skyscraper), but it is also useful for flying around in atmosphere. Surely, you need artifical gravity to keep crew on decks and some anti-inertial system to prevent them from falling towards back of the ship, but you need that second one for FTL anyway, right? And even if the first one consumes a lot of energy, it might be useful to "reduce" weight of the ship on planet (by lowering the local gravity). In my 'verse, there is a saying: Combat, Drive, Gravity, pick any two.
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Post by bigbombr on Dec 1, 2019 9:25:54 GMT
srbrant: I am also working on a sci-fi story (main caracter's name is my username), and it has many elements similar to yours (although it is set in cca. 22nd century, and arfical gravity is much more expensive). The horizontal layout is surely useful for cargo transport (try stacking containers to a skyscraper), but it is also useful for flying around in atmosphere. Surely, you need artifical gravity to keep crew on decks and some anti-inertial system to prevent them from falling towards back of the ship, but you need that second one for FTL anyway, right? And even if the first one consumes a lot of energy, it might be useful to "reduce" weight of the ship on planet (by lowering the local gravity). In my 'verse, there is a saying: Combat, Drive, Gravity, pick any two. Stacking crates is easy. Bending spacetime to get gravity without constant acceleration, a stupendous amount of mass-energy or spin is impossible. Also, for flying landers though atmosphere: the Falcon 9 seems to manage just fine, despite being a wingless tailsitter. IMO, belly landers don't make much sense and are grossly overrepresented in modern science fiction. It also doesn't make sense not to use your main drive for landing.
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Post by AtomHeartDragon on Dec 1, 2019 11:46:11 GMT
srbrant: I am also working on a sci-fi story (main caracter's name is my username), and it has many elements similar to yours (although it is set in cca. 22nd century, and arfical gravity is much more expensive). The horizontal layout is surely useful for cargo transport (try stacking containers to a skyscraper), but it is also useful for flying around in atmosphere. Surely, you need artifical gravity to keep crew on decks and some anti-inertial system to prevent them from falling towards back of the ship, but you need that second one for FTL anyway, right? And even if the first one consumes a lot of energy, it might be useful to "reduce" weight of the ship on planet (by lowering the local gravity). In my 'verse, there is a saying: Combat, Drive, Gravity, pick any two. Stacking crates is easy. Bending spacetime to get gravity without constant acceleration, a stupendous amount of mass-energy or spin is impossible. Also, for flying though atmosphere: the F9 seems to manage just fine, despite being a wingless tailsitter. IMO, belly landers don't make much sense and are grossly over represented in modern sciencefiction. It also doesn't make sense not to use your main drive for landing. Stacking crates: Just have a crane and/or ramp + big cargo door. You are going to have to haul all that stuff up the gravity well anyway, so it's not like you are pointlessly wasting energy hauling it up a tall vehicle. You could also have cargo bay near the ground level and engines on the sides or top. Some considerations for belly landers: - Your main drive would be very hard on landing site and cannot switch gears. You could have a ventrally mounted softer liftoff/landing drive to clear the ground. An example configuration would be ventral liftoff drive, aft maneuvering (and combat if applicable) drive (also used after clearing the ground to boost to orbital velocity), again ventral low-thrust, high-isp cruise drive (to keep the floor the way it was when landed). You can swap the liftoff drive for wheels and a runway if you want to.
- Stability when landing rough. Note that you need VTOL for that, so no swapping liftoff drive for a runway. You can have stable tailsitter, but it will require long, splayed landing legs - depending on the rest of considerations, either configuration could be more practical.
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